Hypodermic syringe



March 1942 c. A. CLERICI HYPODERMIC SYRINGE Filed Aug. 14, 1940 CHARLESA. CLERICL INV ENT OR.

m m A Patented Mar. 17, 1942 ;2 i

UNITED STATES e PATENT TQFFICE HYPODERMIC SYRNG' y Charles Abraham Clerici, Nashville, Tenn., as

or to Eisele & Co., Nashville, Tenn.,' a co'r.. w po-ation of Delaware v ,v 7 I PDI c t-inAu uSt 14, 1940, se taNo352,492' v Thisf inventionrelates to the manufacture of hypodermic syringes of glass or like material and particularly to that type of syringe having a conically ground nozzle adaptedto receive the hub of a suitable hypodermicneedle.

Heretofore, syringes of this type have usually been prepared by forming a conical nozzle blank upon the end of the barrel by the application of suitable shaped tools after the glass has been softened by heating it. This nozzle blank was 10 The upper frustum |5 is the unground portion given the approximate shape of the finished of the original nozzle blank while the frustum ground nozzle, i. e., a frustum of a cone having [6 is the ground portion The intersection l'l its larger base adjacent the syringe barrel, exof the surfaces of the two frustums will not be a cept that a certain amount of extra glass was sharp line of demarcation but will be a zone of allowed to be removed by the grinding operation. relatively gradual e g g from grou d to A portion of the blank was then ground to the ground surface as wi now be explained. final proper conical shape and dimensions by The grind'ng tool !4 is so shaped that at the means of a grinding tool and abrasive material. finish of the grinding operation its end having Due to this operation a shoulder or ridge was the larger opening Will pr j Over the unground formed at the boundary line on the blank where por o of t e b The angles o taper Of the the ground and unground portion met. Due to two frustums are very small so that the angle the abrupt change in diameter at this point and between the interior grinding surface of the tool to the fact that the skin of the glass had been |4 and the surface of the unground frustum !5 ground away, this region was relatively weak will be very small. The abrasive material used and breakage at this point was frequent. contains an assortment of sizes of grains and it It is an object of this invention to eliminate Will thus be seen that as the grndin ope t n this weak point by causing the line of demarcaproceeds, that while all sizes of abrasive grains tion between the ground and unground portions are effective in grinding the surface of frustum of said nozzle to be, not a shoulder, a groove or a |6. only the larger grains are eifective to grnd definite line, but a Zone of appreciable width upon the lower portion of frustum !5, i. e., only through. which the ground surface gradually those grains of a diameter sufficient to reach merges into the unground surface, thus preventacross from the surface of the grinding tool !4 ing localization of strains which always precedes to the surface of the frustum !5. As the ina break. terior surface of the tool |4 and the exterior The method by which I accomplish this result surface of frustum |5 are divergent it will be is best understood by reference to the accomseen that progressively larger gra'ins are repanying drawing in which Figure 1 represents quired to span the gap and since these sizes form in elevation the blank formed in accordance a dimin'shing proportion of the abrasive matewith my invention, and Figura 2 represents a rial, the amount of grinding done on the lower similar View of the completed product. 40 portion of frustum |5 will gradually diminish In the drawing the numeral Io denotes the usual syringe barrel having the interiorly ground piston receiving cylinder ll. Projecting from the lower end of the barrel o is the nozzle blank blank, -i,e.,: the larger portion of the conical grinding 'surface faces the nozzle barrel. The application of this grindng tool grinds the lower end of the nozzle blankglz into the form of a frustumof a cone but With'a taper the reverse' of the original taper. Thus, the nozzle tip is left in its final form of two frustums joined end to end at their larger bases and joined to the syringe barrel by the smaller base of one of them.

in a direction toward the syringe barrel o. 'I'hus the fully ground surface of frustum !6 will gradually merge into the unground surface of frustum !5 and no sharp line of demarcation is produced.

z which is of the form of a, fru tum of c n Due to the inaccuracies always present in the with its smaller base next adjacent the syringe surface of the blank and to the practically barrel w. I form this blank by applying to the mathematical perfection of the ground surface softened hot glass suitable moulding tools in a of the frustum !6 the zone of merger between manner Well known in the art. A duet I 3 is the two surfaces Will vary along the length of formed through the center of the nozzle blank. the tip in a somewhat haphazard fashion thus I next apply to the nozzle blank a grinding further distributing the strains which tend to tool !4, charged with suitable abrasive, which cause breakage. tool is provided with an interior conical grind- It will be seen that the crux of my invention ing surface. The taper of this conical surfac lies in the provision of the slight angle between is, however, the reverse of that of the nozzle the surface of the ground and unground portion.

While I have shown two frustums taperng in opposite directions it is evident that this result would also be obtained by making frustum |5 in the form of a cylnder or even a frustum tapering in the same direction as frustum !6 but with a smaller angle'. The method shown and described, however, is my preferred form.

It is of course obvious that .these .as -well as other details of' my method may be'vared to suit the individual requirements of manufacture without departing from the spirits of my invention. I therefore desire the above description and accompanying drawing to be' considered as illustrative and not restrictive,v ..my invention being limited only by the scope .of .the appended claims.

I claim as my invention:

1. In the manufacture of hypodermicsyringes having a needle-hub receiving nozzle, the steps which comprise the formng of a nozzle blank, the application thereto `of a grinding tooloharged with suitable abrasve and 'having an internally tapered grinding surface, the angle formed between the two opposite sides of the grinding surface being differerit'irom the angle ground areas of said tip which comprises the application to said tip of a grinding member `charged with a suitable abrasive material and having a tapered internal surface of such form and dimension that upon completion of the .grinding operation aportion of said internal sur- 'face 'will overlie 'and gradually diverge from, at

a very'small angle, the unground portion of said tip, said angle of divergence being of such order that a -gradually decreasing proportion of the abrasvematerial willbe o'f sufficient size to span the-gap'between the' two-surfaces and'be effective as a grinding' agent.

CHARLES CLERICI. 

